This invention relates to the removal of pollutants from gases and more particularly to an adsorber system in which pollutant laden gases are passed through columns of activated char to adsorb the sulfur oxides from the gases into the char pellets.
The technique of adsorbtion to remove sulfur oxides from pollutant laden gases, such as flue gases from a fossil fuel boiler, is well known. According to this basic process, an adsorber is provided which receives the gases and includes a bed of activated char located in the path of the gases. As a result, the SO.sub.2, oxygen and water vapor in the gases come into contact with and are adsorbed by the char pellets. The SO.sub.2 in the gases is oxidized to SO.sub.3 and subsequently catalytically converted to sulfuric acid which is held in the interior pore system of each char pellet. The substantially pollutant-free gases are then passed to a stack, or the like, for exhaustion into the atmosphere.
The adsorber usually contains one or more vertical beds of activated char which moves downwardly in mass flow while adsorbing the pollutants from the gases. The upper portion of the char bed is continuously replenished while the saturated char is collected at the bottom and sent by conveyors to other sections of the system. For example, the saturated char can be sent to a regenerator for regenerating the saturated char by thermal or wet regeneration to reverse the reactions taking place in the adsorber and produce a concentrated steam of SO.sub.2, H.sub.2 O, CO.sub.2, and N.sub.2. The stream of SO.sub.2 can then be further treated to produce relatively pure sulfur.
In these type of arrangements precautions must be taken to insure a steady flow of the gases from the boiler directly to the stack in the event of a malfunction of either the adsorber section, the regeneration section, or the additional section utilized for further treatment of the sulfur gases. In some arrangements the adsorber is generally placed in a gas flow circuit extending parallel to the main circuit connecting the boiler to the stack and dampers and bypass lines are used to selectively route the gases to the adsorber or directly to the stack. This of course requires additional, rather elaborate, ducting along with dampers, fans, and other associated components to achieve the system design requirements. In addition to being costly these type of arrangements are cumbersome and require a relatively large amount of additional components and labor to assemble them.